Net Loss Per Share (Tables)

12 Months Ended

Dec. 31, 2018

Earnings Per Share [Abstract]

Weighted-Average Equity Instruments Excluded from Calculation of Diluted Net Loss Per Share

The following weighted-average equity instruments were excluded from the calculation of diluted net loss per share because their effect would have been anti-dilutive for the periods presented:

	Year Ended December 31,
	2018		2017		2016
Series A convertible preferred stock		—		—		611,392
Series B convertible preferred stock		—		—		1,407,097
Unvested restricted common stock		26,841		57,629		100,634
Options to purchase common stock		3,014,984		2,043,420		1,063,778